Converting Bulk Ec To Pore Ec - Decagon Devices 5TE Operator's Manual

5TE Operator's Manual
3.Theory
polar molecules that are in solution. EC is measured by
applying an alternating electrical current to two electrodes,
and measuring the resistance between them. Conductivity is
then derived by multiplying the inverse of the resistance
(conductance) by the cell constant (the ratio of the distance
between the electrodes to their area).
The 5TE uses a 2-sensor array to measure the EC. The array
is located on the screws of two of the 5TE prongs. Small
amounts of oil from skin contact with the screws will
cause significant inaccuracy in the EC measurement.
See the sensor cleaning section at the end of this manual for
instructions on cleaning the sensors if contamination occurs.
The 5TE uses a two electrode array to measure the bulk EC
of the surrounding medium. The bulk EC measurement is
calibrated at the factory to be accurate within ±10% from 0
to 7 dS/m. This range is adequate for most field, greenhouse
and nursery applications. However, some special applica-
tions in salt affected soils may requires measurements with
bulk EC greater than the specified range. The 5TE will mea-
sure up to 23.1 dS/m bulk EC, but user calibration is
required above 7 dS/m. Additionally, EC measurements
above 7 dS/m are very sensitive to contamination of the
electrodes by skin oils, etc. Be sure to read sensor cleaning
section at the end of the manual if you plan to measure the
EC of salty soils.

Converting Bulk EC to Pore EC

For many applications, it is advantageous to know the elec-
trical conductivity of the solution contained in the soil pores
(σ ), which is a good indicator of the solute concentration in
p
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